Once upon a time all the spirits set about building two palaces; a palace of truth, and a palace of lies. Every time a child told the truth, a brick was created for the palace of truth. The spirits of truth would then take it and add it to the growing walls. In just the same way was the palace of lies built. Each brick was created when a child told a lie. Both palaces were impressive - the best in the world - and each group of spirits worked hard to try to make sure that their own palace was the best. So much so that the lying spirits, who were much more tricky and deceitful, sent a group of spirits to the world to get children to tell more and more lies. These spirits were successful, and started getting many more bricks. As a result, their palace became bigger and more spectacular. But one day, something strange happened in the palace of lies. One of the bricks turned into a cardboard box. A little later another brick turned into sand, and then another turned into glass, and smashed. And so, little by little, it became clear that whenever a lie was discovered, the brick that it had created changed its form, was crushed, and finally disappeared. In this way, the palace of lies became weaker and weaker, and in the end it completely fell to pieces. 
Understood that you cannot use lies for anything. 